Latest ArticlesThe treatment of anionic 99TcO4- in the waste tank with high alkalinity is still very challenging. In this work, a new temperature-responsive alkaline aqueous biphasic system (ABS) based on (tri-n-butyl)-n-tetradecyl phosphonium chloride (P44414Cl) was developed to remove radioactive 99TcO4-. The phase transition mechanism was studied by cloud point titration, small-angel X-ray scattering, dynamic light scattering, and molecular dynamic simulations. As the NaOH concentration or temperature increased, the P44414+ micelle could grow and aggregate. This micelle showed a particularly high affinity toward ReO4-/99TcO4- compared to other competing anions and could directly extract more than 98.6% of 99TcO4- from simulated radioactive tank waste supernatant. Furthermore, the loaded 99TcO4- could be easily stripped by using concentrated nitric acid rather than metal salt-based reductants. This work clearly demonstrates that the alkaline ABS is a promising separation system for solving the technetium problem in the alkaline waste tank.
In this work, a technique was proposed to prepare UO2 from UO3 by the two processes of fluorination reaction of UO3 with NH4HF2 and electrochemical reduction of UO22+ for the recycle uranium. The feasibility of fluorination reaction was firstly confirmed using thermodynamic calculation; then, the products were analyzed using XRD, Raman and fluorescence to be UO2F2. The fluorination mechanism was inferred to be UO3(s) + NH4HF2 → (NH4)3UO2F5→ NH4(UO2)2F5 → UO2F2. The redox behavior of UO22+ on W electrode was investigated by cyclic voltammetry and square wave voltammetry, which indicated that UO22+ was reduced to UO2 via a two-step single electron transfer with diffusion-controlled. The diffusion coefficient of UO22+ was calculated to be 6.22 × 10−5 cm2/s. The disproportionation reaction of UO22+ was observed, and the relationship between the disproportionation reaction and scan rate was discussed. Moreover, the electrochemical fabrication of UO2 was conducted by electrolysis at −0.8 V, and the product was analyzed by XRD, SEM and EDS to be UO2. ICP-AES results showed that the extraction efficiency of UO2 could reach 98.53%.
Due to the rigid Si-O-Si backbone, silicone rubber (SR) have a widespread application in extreme environment such as high temperature and high-level radiation. However, the radiation stability of SR still does not meet the practical needs in special radiation environments. Herein we prepared epoxy POSS(ePOSS)/SR nanocomposites with excellent thermal stability and radiation resistance. As a physical crosslinking point in the SR, addition of small amount of ePOSS not only enhanced the mechanical properties of the matrix, but also improved its thermal stability greatly due to their good compatibility. ePOSS/SR had higher radiation stability in air than SR owing to the inhibition of radiation oxidation by ePOSS, and the yield of main gaseous radiolysis products (CH4, H2, CO and CO2) of SR and ePOSS/SR nanocomposites was determined. By analyzing the changes of chemical structure, thermal properties and mechanical properties of the ePOSS/SR nanocomposite, combined with the characteristics of gas products after γ-irradiation, the radiation induced crosslinking and degradation mechanism of the nanocomposites was proposed comprehensively.
During the chemical weathering of the uranium mill tailings, released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides. A deeper understanding of the interaction between uranium and common oxyhydroxides under environmental conditions is necessary. In this work, uranium sorption behaviors on Al-, Mn- and Fe-oxyhydroxide minerals (boehmite, manganite, goethite, and lepidocrocite) were investigated by batch experiments. Results showed that the uranium sorption on Al-oxyhydroxide behaved significantly differently from the other three minerals. The sorption edge of the Mn- and Fe-oxyhydroxides located around pH 5, while the sorption edge of boehmite shifted about 1.5 pH unit to near neutral. The sorption isotherms of uranium on manganite, goethite and lepidocrocite at pH 5.0 could be well fitted by the Langmuir model. Instead of surface complexation, sorption on boehmite happened mainly by uranium-bearing carbonates and hydroxides precipitation as illustrated by the characterization results. Both carbonate and phosphate strongly affected the uranium sorption behavior. The removal efficiency of uranium by boehmite exceeded 98% after three sorption-desorption cycles, indicating it may be a potential material for uranium removal and recovery.
Carbohydrate antigen 19-9 (CA19-9) with multi epitopes relatively high expresses on colorectal cancer (CRC) cells, making it an attractive target for developing radioimmunotherapy (RIT) for CRC. The lutetium-177 (177Lu) labeled monoclonal antibodies (mAbs) can selectively bind the corresponding antigens and release targeted cytotoxic radiation, which could induce cell apoptosis and reduce the drug-induced resistance. Here, a series of CA19-9 mAbs were labeled with zirconium-89 (89Zr), and one with high tumor uptake was screened via PET imaging, which has potential application for the diagnosis of CRC. Then the screened mAb (C003) labeled with 177Lu was utilized for CA19-9 targeted RIT, which presents a significant suppression effect on the growth of colo205 xenografts than immunotherapy alone. Meanwhile, the side effects of 177Lu-DOTA-C003 are limited according to the results of in vivo study. Both 89Zr-DFO-C003 for CRC immune-PET imaging and 177Lu-DOTA-C003 for RIT against CRC exhibit good potential in clinical applications.
Two tetravalent uranium silicate and germanate M2UIVT3O9 (M = K, Cs; T = Si, Ge) crystals were crystalized under inert gas by molten salt flux growth method. K2USi3O9 (1) crystallizes in the monoclinic space group P121/n1 with lattice parameters a = 7.1076 Å, b = 10.4776 Å, c = 12.2957 Å, γ = 120° and V = 915.67 Å3. Cs2UGe3O9 (2) crystallizes in a hexagonal space group P-6 with lattice constants of a = 7.5138 Å, b = 7.5138 Å, c = 11.0114 Å, γ = 120° and V = 538.38 Å3. Bond valence calculations indicate tetravalent uranium in both structures, which contain three-membered single-ring T3O96− trimers. K2USi3O9 is the first uranium silicate that contains the Si3O96− trimers.
While radiotherapy is a mainstay therapeutic modality for malignant tumor, the intrinsic tumor resistance to radiotherapy, as well as the concomitant radiation injury to adjacent healthy tissues, greatly limits the efficacy of cancer radiotherapy. As a result, the development of novel radioenhancers and radioprotectants is highly desired for clinical radiotherapy. In recent years, nanozymes have inspired ever-growing research interest because of their multi-enzyme activities and microenvironment-responsive feature. In view of the significant progress of nanozymes in radiation medicine, we, in this review, systematically illustrate the impressive progress of nanozymes for potentiating radiotherapy and radiation protection. First, the types of nanozymes used in tumor radiotherapy are briefly discussed. Subsequently, the main strategies of nanozymes to enhance the radiotherapy efficiency, including promoting the generation of reactive oxygen species (ROS), relieving hypoxia in tumor microenvironment and combining with other cancer therapeutic regimens, are summarized. Finally, the advances of typical nanozymes for preventing radiation-induced hematopoietic damage and gastrointestinal damage are highlighted.
The prevalence of positron emission tomography (PET) imaging has advanced biomedical applications for its ultrahigh sensitivity, deep tissue penetration and quantitative visualization of diseases in vivo. 64Cu with ideal half-life and decay characteristics has been designed as radioactive probes for disease diagnosis. The currently reported 64Cu-labeled nanomaterials have the advantages of long circulation time in serum, good biocompatibility and mature preparation methods, and have been used in vivo PET imaging, biodistribution and pharmacokinetic monitoring, and imaging guided therapy. At the same time, suitable carrier characteristics and radiolabeling strategies are particularly important in the 64Cu PET imaging process. In this review, we summarize different imaging probe designs and 64Cu radiolabeling strategies, as well as their eventual applications in biomedicine. The potential challenges and prospects of 64Cu labeled nanomaterials are also described, which provides broad prospects for radiolabeling strategies and further applications.
Nitrogen enrichment and increased nitrogen content is an effective strategy for enhancing adsorption of uranium by carbon nitride polymers. Herein, we reported the uranium absorption by using a structurally well-defined and nitrogen-rich carbon nitride polymer with C3N5 stoichiometry for the first time. In comparison with the adsorption performance of g-C3N4 for U(VI), the conjugation system of the material was increased by connecting the heptazine unit through the azo bridge in the structure of C3N5, so that C3N5 exhibited several times higher adsorption performance than that of g-C3N4. The C3N5 has high kinetics for uranyl ions, which can adsorb 100 mg/g U(VI) in only 10 min and reach complete adsorption equilibrium in 60 min; the theoretical maximum adsorption capacity is 207 mg/g, meanwhile, the material exhibits high selectivity. The results of spectral analysis and theoretical calculations indicate that the process of uranyl ion capture by C3N5 is a combination of physical and chemical adsorption, and its higher density of electronic states makes the electrostatic binding ability enhanced, which is favorable to the adsorption of uranyl ions by C3N5. This work indicates that C3N5 has great promise and application in the separation and enrichment of uranyl ions, and also provides a reference for the systematic investigation of the adsorption ability of nitrogen-rich carbon nitrogen polymers on uranyl ions.
Exploring efficient materials for capturing radioactive iodine in nuclear waste is of great significance for the progress of nuclear energy as well as the protection of ecological environment. Covalent organic frameworks (COFs) have emerged as promising adsorbents because of their predesignable and functionalizable skeleton structures. However, it remains a grand challenge to achieve large scale preparation of COFs. In this work, we developed a mild and efficient microwave irradiation method instead of the traditional solvothermal method to prepare copper phthalocyanine-based covalent organic frameworks (CuPc-COFs) within only 15 min. The nitrogen-rich 1, 2, 4, 5-tetracarbonitrilebenzene (TCNB) was selected as the solely organic ligand to construct copper phthalocyanine-based 2D conjugated COFs. The resultant CuPc-COFs exhibited excellent iodine enrichment with 2.99 g/g for volatile iodine and 492.27 mg/g for iodine-cyclohexane solution, respectively, outperforming that of many porous materials. As indicated by spectroscopic analysis and DFT calculations, this impressive adsorption performance can be attributed to the charge transfer arising from nitrogen-rich phthalocyanine structures and electron-rich π-conjugated systems with iodine molecules. Moreover, the strong electrostatic interaction between Cu(II) on chelate centers and polyiodide anions (Ix-) also play an important role in the firmly trapping radioactive iodine. Therefore, this study provides a facile and intelligent approach to implement metal-based COFs for the remediation of toxic radioactive iodine.
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